Worm castings contain many beneficial bacteria. These bacteria are responsible for turning ammonium in soil into nitrates. Nitrates are the most easily used form of nitrogen for the plants. As well as containing these beneficial bacteria, they also contain amino acids which help in the growth and development of your plants. For hydroponics, worm castings are available in liquid form to cover all stages of plant development or additives to give your plants an added boost. Worm castings are a cost efficient way of supplying the needed nutrients to the plants and in most places are readily available.